AS3524A-ZC21T View Datasheet(PDF) - austriamicrosystems AG
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Description
Manufacturer
AS3524A-ZC21T Datasheet PDF : 124 Pages
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AS3524 C21 / C22
Data Sheet, Confidential
austriamicrosystems
5.1.6 Boot Concept
It can be selected if the system should boot either using the internal ROM (internal boot loader) or an external ROM/Flash (connected to the MPMC
interface). XPC[0] is read within global chip reset to do the selection of either internal or external boot.
Table 7 Boot definitions for internal/external boot selection
XPC[0]
1
0
Booting Option
Internal ROM
External ROM/Flash
For the internal bootloader, two chip versions are available: C21 and C22. Version C22 has additional features and is fully backward compatible to
C21.
5.1.6.1 Internal Bootloader Version C21
Within the internal ROM boot loader several options for booting can be selected:
• SSP IF - SPI master for ST serial flash types
• SSP IF - SPI slave
• NandFlash
• Debug UART diagnostics
All boot loader options of the internal bootloader are configured by XPC[3:1] pins. External pull-up or pull-down resistors should be used to
configure the boot options.
Table 8 Boot definitions Chip version C21
XPC[3:1]
0
000
1
001
2
010
3
011
4
100
5
101
6
110
7
111
Boot Device
SPI master ST M25Pxx serial Nor Flash
reserved
SPI slave
NandFlash (SB/BB - autodetect)
NandFlash (SB/BB - autodetect)
UART / Command Line Interface without diagnostics
UART / Command Line Interface without diagnostics
UART / Command Line Interface with diagnostics
5.1.6.2 Internal Bootloader Version C22
For chip version C22 the boot loader is extended with two additional features
• IDE boot: direct boot from harddisk
• USB boot promer. In the case that a USB connection is present and either an update button is pressed or there is no bootable device, the
USB promer is started (see Figure 5 Boot decision between normal boot and USB boot promer” for details). The USB boot promer allows
update of the firmware by using an USB mass storage class device. This update can be used either for initial programming (factory
programming) or as mechanism for an in-field firmware update.
The C22 boot loader is fully compatible to the C21 boot loader except for mode 4, where the previous NAF boot mode is replaced by IDE boot. For
version C22, NAF boot is only available in mode 3. Refer to Table 9
Boot definitions Chip version C22” for details.
The update button is located between xpa[4] and xpa[0]. Within the key scan routine, xpa[4] is driven shortly to each logic level “0” and “1” and the
value of xpa[0] is read back to sense a keypress of the update button.
For the USB promer, it is necessary that frequency settings defining the quarz crystal frequency are defined by the pins xpc[3:1]. For details refer to
“Table 10 USB promer frequency settings”. These settings are read at the beginning in the initialisation routine of the bootloader.
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